Elizabeth Michelle Sullivan
Elizabeth Michelle Sullivan, who a friend reported missing in October 2014. Authorities located her decomposed body two years later. Photo courtesy of SDPD

A jury convicted a former member of the military of second-degree murder Friday for fatally stabbing his estranged wife and mother of his two children.

Authorities located the body of Elizabeth Sullivan, 31, in San Diego Bay nearly two years after she vanished in Oct. 2014.

Prosecutors allege Matthew Scott Sullivan, 35, killed his wife at the couple’s Liberty Station home. They say he kept her body hidden in a freezer for nearly two years before dumping it.

Jurors acquitted Sullivan of a first-degree murder charge, following a three-week trial and just over a day of deliberations. In addition to the second-degree murder count, they convicted him of an allegation of using a knife in his wife’s killing.

A judge set sentencing for April 13.

Deputy District Attorney Jill Lindberg alleged at trial that Sullivan stabbed his wife at least five times in her bedroom.

She said Sullivan hid the body and murder weapon inside his home until he was compelled to discard Elizabeth’s remains when movers arrived in October 2016. He planned a cross-country move to the East Coast.

Her decomposed body was discovered that same day in the water about a half-mile from their residence. She was dressed in the same clothes she was last reported wearing.

An autopsy revealed a series of injuries to her ribs. The prosecutor described them as consistent with stab wounds. Elizabeth also suffered fractures in her jaw and her nose.

Investigators discovered the victim’s blood beneath the carpet in her bedroom. It also stained a knife in the attic of the couple’s home, according to Lindberg.

Defense attorney Marcus DeBose argued that the blood stemmed from self-inflicted cutting. He argued Elizabeth had a reported history of depression and self-harm.

DeBose said that about a month before her disappearance, Sullivan had discovered that his wife had cut herself. She bled heavily throughout her bedroom, he told the jury.

DeBose suggested that Elizabeth stashed the knife to keep her cutting behaviors secret. If her husband was guilty, he argued, he could have disposed of the weapon at any time.

The attorney also said his client’s wife had a substance abuse problem and frequently disappeared without notice. DeBose said she’d previously talked to her father and friends about leaving Sullivan and their two children.

On the night of Oct. 13, 2014, DeBose told jurors Elizabeth simply left home and never returned.

The prosector, however, told jurors that the victim never contacted anyone after that night. Nor did she claim about $1,000 she transferred from the couple’s joint account to her personal bank account. She made the transaction shortly before her disappearance.

The Sullivans’ marriage fell apart over financial issues and Elizabeth’s affair with another man, Lindberg said. The development led the couple to start sleeping in separate bedrooms.

Sullivan arranged for his mother and sister to move into the Liberty Station home on Oct. 13 to begin caring for their children. His wife responded by contacting an attorney, Lindberg said. Elizabeth secured a restraining order to keep her husband’s family out.

The prosecutor alleged Sullivan also feared she might take his children in a divorce.

“His back was against the wall. He had to do something to stop her, so he did,” Lindberg told the jury.

After Oct. 13, one of the victim’s friends, who knew she was planning to leave Sullivan, couldn’t reach her. The friend reported her missing.

Sullivan did not summon police about her disappearance. Lindberg noted though that he did go to a store the morning of Oct. 14 to purchase a single item – carpet cleaner.

Investigators searched the home in 2014, when it was still a missing persons case. They found an empty freezer in the garage, Lindberg said, but nothing that could lead to an arrest.

A former San Diego County deputy medical examiner who helped conduct the autopsy testified that the victim’s decomposition was more consistent with someone who had been dead for one to two months.

Lindberg said Sullivan likely utilized the freezer to hide the body, which accounted for the delayed decomposition. DeBose called that theory speculation.

The prosecutor said a police cadaver dog alerted officers to the presence of a dead body in Sullivan’s garage during the 2016 investigation. She said that indicated the body had been hidden in the freezer there and was recently moved.

Police arrested the defendant in 2018 at his home in Delaware. Authorities returned him to San Diego.

– City News Service